1. Technical Field
The present invention relates to a motion analysis apparatus using an inertial sensor and a motion analysis method.
2. Related Art
An apparatus that measures a motion of an object and analyzes the motion is necessary in various fields. For example, in the sport field, motions of a golf club, a tennis racket or the like are measured to analyze a swing track, and motions of arms and legs in running are measured to analyze a running form in some cases. Thus, what needs to be improved becomes clear by reviewing the analysis result and this results in the improvement of athletic performance.
These days, an optical motion capturing apparatus has been proposed as a practical motion analysis apparatus. In this apparatus, in general, a measurement object to which a marker is attached is continuously photographed by an infrared camera or the like, and a movement track of the marker is calculated using the photographed continuous images to analyze a motion of the measurement object (see JP-A-2010-110382). On the other hand, in recent years, an apparatus has been proposed in which a small inertial sensor is attached to a measurement object and a motion of the measurement object is analyzed from output data of the inertial sensor (see JP-A-2008-073210). This apparatus has an advantage in that an infrared camera is not necessary and handling is easy.
When an angular velocity sensor (gyro sensor) is used as an inertial sensor that is attached to a measurement object, for example, it is necessary to remove a bias value of the angular velocity sensor. The bias value collectively refers to errors including a zero bias in an initial state where the angular velocity is zero and a random drift due to external factors such as power fluctuation or temperature change. To calculate the bias value, it is necessary to detect an angular velocity in a state where the measurement object is stopped. However, for example, in the case of sports field, it may be unnatural and difficult to have the measurement object in a temporary stop to obtain the bias value.